2018 Atlantic hurricane season (Bob's official prediction)
The 2018 Atlantic hurricane season featured slightly below average activity, and was much less active than the previous season. A total of 12 tropical cyclones formed, all of which strengthened into tropical storms. Of the 12 tropical storms, 5 became hurricanes and 2 became major hurricanes. The strongest storm of the season was Hurricane Helene, which peaked as a Category 4 hurricane southwest of Bermuda. The season was slightly below average because of a weak Modoki El Niño event developing late in the season, as well as an Atlantic sea surface temperature pattern resembling the negative phase of the Atlantic Multidecadal Oscillation. This supressed activity in the tropical latitudes, with only one hurricane forming south of 20°N. The season also had the earliest end since the 2006 season, as unfavorable conditions became established in October. Seasonal summary ImageSize = width:700 height:225 PlotArea = top:10 bottom:80 right:20 left:20 Legend = columns:3 left:30 top:58 columnwidth:225 AlignBars = early DateFormat = dd/mm/yyyy Period = from:01/05/2018 till:01/12/2018 TimeAxis = orientation:horizontal ScaleMinor = grid:black unit:month increment:1 start:01/05/2018 Colors = id:canvas value:gray(0.88) id:GP value:red id:TD value:rgb(0.38,0.73,1) legend:Tropical_Depression_=_≤39_mph_(≤62_km/h) id:TS value:rgb(0,0.98,0.96) legend:Tropical_Storm_=_39–73_mph_(63–117_km/h) id:C1 value:rgb(1,1,0.80) legend:Category_1_=_74–95_mph_(118–153_km/h) id:C2 value:rgb(1,0.91,0.46) legend:Category_2_=_96–110_mph_(154–177_km/h) id:C3 value:rgb(1,0.76,0.25) legend:Category_3_=_111–129_mph_(178–208_km/h) id:C4 value:rgb(1,0.56,0.13) legend:Category_4_=_130–156_mph_(209–251_km/h) id:C5 value:rgb(1,0.38,0.38) legend:Category_5_=_≥157_mph_(≥252_km/h) Backgroundcolors = canvas:canvas BarData = barset:Hurricane bar:Month PlotData= barset:Hurricane width:11 align:left fontsize:S shift:(4,-4) anchor:till from:25/05/2018 till:31/05/2018 color:TS text:Alberto (TS) from:16/06/2018 till:18/06/2018 color:TS text:Beryl (TS) from:21/07/2018 till:24/07/2018 color:TS text:Chris (TS) from:08/08/2018 till:15/08/2018 color:C1 text:Debby (C1) from:20/08/2018 till:28/08/2018 color:C2 text:Ernesto (C2) from:31/08/2018 till:08/09/2018 color:C3 text:Florence (C3) barset:break from:06/09/2018 till:09/09/2018 color:TS text:Gordon (TS) from:13/09/2018 till:20/09/2018 color:C4 text:Helene (C4) from:16/09/2018 till:17/09/2018 color:TS text:Isaac (TS) from:27/09/2018 till:04/10/2018 color:C1 text:Joyce (C1) from:12/10/2018 till:14/10/2018 color:TS text:Kirk (TS) from:19/10/2018 till:23/10/2018 color:TS text:Leslie (TS) bar:Month width:5 align:center fontsize:S shift:(0,-20) anchor:middle color:canvas from:01/05/2018 till:01/06/2018 text:May from:01/06/2018 till:01/07/2018 text:June from:01/07/2018 till:01/08/2018 text:July from:01/08/2018 till:01/09/2018 text:August from:01/09/2018 till:01/10/2018 text:September from:01/10/2018 till:01/11/2018 text:October from:01/11/2018 till:01/12/2018 text:November TextData = pos:(480,30) text:"(From the" pos:(528,30) text:"Saffir–Simpson hurricane wind scale)" The 2018 Atlantic hurricane season officially began on June 1, and ended on November 30. However, the season started with a pre-season storm for the fourth year in a row, with Subtropical Storm Alberto forming on May 25 (though it later was classified as a tropical storm in post-analysis). It was a near average season in which 12 tropical cyclones formed. The last storm dissipated on October 23, when Tropical Storm Leslie transitioned into an extratropical cyclone. All 12 of these tropical cyclones became named storms, 5 of which became hurricanes and 2 of which became major hurricanes. Although some groups (such as Colorado State University) initially predicted above average activity this season, the anomalously cool tropical Atlantic, as well as a rapid developing weak El Niño event, limiting activity to slightly below average levels. As a result, wind shear was stronger than normal in the tropical latitudes, and mid-level dry air also limited the season from being more active. Storms Tropical Storm Alberto A Central American Gyre (CAG) developed in late May. A broad area of low pressure formed over the Northwestern Caribbean Sea, developing into Subtropical Storm Alberto on May 25. Alberto initially struggled to strengthen as it encountered multiple center relocation, but finally began to strengthen on May 27 as it strengthened into a tropical storm. Operationally, Alberto was assessed to have been a subtropical storm at peak, but post-analysis reclassified Alberto as tropical over the northern Gulf of Mexico. Alberto reached its peak intensity early on May 28 with maximum sustained winds of 65 mph (105 km/h) and a minimum pressure of 990 mb. This made Alberto the second strongest May Atlantic tropical cyclone by pressure. Alberto made landfall at 21:00 UTC the next day over the western Florida Panhandle, with maximum sustained winds of 45 mph. Alberto weakened into a tropical depression early on May 29, and managed to maintain tropical depression status until it transitioned into a post-tropical cyclone over Michigan on May 31. Tropical Storm Beryl A broad area of low pressure formed over the Northwestern Caribbean Sea on June 14. The low pressure area became more concentrated on June 15 as it emerged into the Bay of Campeche and a tropical wave entered the area. The disturbance organized into the second tropical depression of the season at 18:00 UTC on June 16, and strengthened into Tropical Storm Beryl six hours later. In an environment with warm water and moderate wind shear, Beryl slightly strengthened to a peak intensity at 00:00 UTC on June 18 with maximum sustained winds of 50 mph (80 km/h). Beryl then made landfall in northern Veracruz at this intensity, and rapidly weakened as it passed over the rough terrain of central Mexico. Beryl dissipated by 12:00 UTC that same day. Tropical Storm Chris After a quiet first half of July, a non-tropical low formed along a decaying frontal boundary off the coast of South Carolina on July 19. This system gradually acquired tropical characteristics, and developed into the third tropical depression of the 2018 season at 06:00 UTC on July 21. Twelve hours later, the depression strengthened into Tropical Storm Chris. Despite moderate southwesterly wind shear and marginally warm sea surface temperatures, slight strengthening ensued thereafter as Chris moved northeastward along the Gulf Stream. Chris acquired its peak intensity by 00:00 UTC on July 23, with maximum sustained winds of 70 mph (115 km/h) and a minimum pressure of 993 mb. At the time, Chris developed an eye-like feature on satellite imagery and the storm was expected to become a hurricane. Instead, Chris began to weaken twelve hours later, and transitioned into an extratropical cyclone by 06:00 UTC on July 24, to the south of Atlantic Canada. The extratropical remnants of Chris made landfall in northeastern Newfoundland, causing minimal damage. Hurricane Debby A tropical wave exited the coast of Africa on July 31. Due to unfavorable conditions, the wave did not develop initially, but finally developed into a tropical depression by 18:00 UTC on August 8 north of Puerto Rico. Although the system was initially expected to strike south Florida as a hurricane, strong wind shear limited strengthening. The depression finally strengthened into Tropical Storm Debby at 00:00 UTC on August 10, but additional strengthening was limited. Debby made landfall in southeastern Florida on August 11 as a minimal tropical storm. After briefly weakening into a tropical depression, Debby regained tropical storm strength late on August 12 and began to rapidly intensify over the warm waters of the Gulf of Mexico. Debby strengthened into the first hurricane of the season at 18:00 UTC on August 13, and reached its peak intensity with maximum sustained winds of 85 (135 km/h) mph and a minimum pressure of 978 mb six hours later as it made landfall in central Louisiana. After landfall, Debby gradually weakened as it turned northeast, dissipating by 18:00 UTC on August 15. Hurricane Ernesto Late on August 14, a vigorous tropical wave exited the coast of western Africa. Due to an outbreak of Saharan Air Layer (SAL) and marginal sea surface temperatures, development was initially slow and the wave struggled to develop deep convection. The wave continued to move rapidly west-northwestward, and finally developed into the fifth tropical depression of the season at 12:00 UTC on August 20 as it entered warmer waters. Intensification was initially slow as Ernesto struggled with dry air entrainment, but a more rapid intensification commenced on August 22 as it moved out of the hostile tropics. Ernesto strengthened into the second hurricane of the season at 18:00 UTC on August 22, but weakened back to a tropical storm six hours later as the circulation became exposed due to moderate southwesterly shear. Shear lessened later that day, and Ernesto regained hurricane strength by 12:00 UTC on August 23. Ernesto rapidly intensified into a Category 2 hurricane six hours later, and reached its peak intensity at that time with maximum sustained winds of 100 (160 km/h) mph and a minimum pressure of 975 mb. After peak intensity, Ernesto begun to weaken as it moved over cooler waters and into increasing shear. However, Ernesto was able to remain a hurricane for several days. Ernesto degenerated into a remnant non-tropical low at 06:00 UTC on August 28 near the Azores as it became devoid of deep convection. Hurricane Florence A tropical wave moved off the coast of west Africa on August 24 at a low latitude. Steered westward with a strong subtropical ridge to its north, the wave moved briskly westward over the tropical Atlantic. The wave developed into Tropical Storm Florence at 18:00 UTC on August 31 south of Barbados. The tropical storm struggled to strengthen over the next few days because of moderate easterly shear and its fast movement, but Florence slowed down its movement on September 3 and became a hurricane at 18:00 UTC that day. In a lower shear environment, Florence rapidly intensified as it turned northward over the Northwestern Caribbean, becoming the first major hurricane of the season at 00:00 UTC on September 5. Florence then reached its peak intensity six hours later, with maximum sustained winds of 120 mph (195 km/h) and a minimum pressure of 962 mb, while located near the Cayman Islands. Florence began to weaken afterward due to increasing shear and an eyewall replacement cycle as it approached the coast of western Cuba. After briefly weakening into a tropical storm on September 6, Florence turned north-northeastward and re-intensified over the Gulf of Mexico to a Category 2 hurricane on September 7. Early on September 8, Florence made landfall over the Big Bend Region of Florida as a Category 1 hurricane. Florence transitioned into an extratropical cyclone at 00:00 UTC on September 9. Tropical Storm Gordon A strong tropical wave moved off the coast of Africa early on September 5, quickly developing into a tropical depression by 12:00 UTC the next day. Due to marginally warm sea surface temperatures and dry air, intensification was slow, though the depression managed to strengthen into Tropical Storm Gordon by 06:00 UTC on September 7. Gordon did not strengthen past 40 mph (65 km/h), and the circulation became exposed on September 8 due to strong wind shear. Gordon maintained tropical depression status until 06:00 UTC on September 9, when it became devoid of deep convection and NHC declared it a post-tropical cyclone. Hurricane Helene Tropical Storm Isaac Hurricane Joyce Tropical Storm Kirk Tropical Storm Leslie Category:2018 Atlantic hurricane season Category:Realistic Category:Predictions Category:Seasons made by Bob